“I have met allies who can report that Russia, as part of their sophisticated information and disinformation operations, engaged actively with so-called non-governmental organisations – environmental organisations working against shale gas – to maintain European dependence on imported Russian gas. At least that’s my interpretation and it adds a new aspect to that information campaign,” he said.

He noted the EU should support the construction of a new gas pipeline to the Caspian sea, bypassing Russia.

He also said the EU should complete energy market liberalisation so that “no one single energy supplier can blackmail any one single nation” in future, alluding to Russian gas supplier Gazprom.

Nato officials later told media the views on shale are Rasmussen’s own and do not reflect the alliance’s official position, but it published an audio file of his Chatham House remarks on its website.

Rasmussen visited London in preparation for a Nato summit in Wales in September.

He said in his Chatham House speech that Russia’s “aggression” against Ukraine is part of a “turning point in history” after the end of the Cold War.

He urged EU countries to follow the example of Poland, Romania, and the Baltic states in boosting defence spending to 2 percent of national GDP.

He also said in the Q and A portion there is “a new build-up” of Russian forces on the Ukraine border in what amounts to keeping “an option open to intervene further in Ukraine”.

He noted that if Russia openly invades its neighbour, it would trigger “deeper, broader, more profound economic sanctions”, but he ruled out a Nato military response saying Nato is “focused on the defence of our allies [members].”

Environmental groups ridiculed Rasmussen’s shale remarks.

“The idea we’re puppets of [Russian leader] Putin is so preposterous that you have to wonder what they’re smoking over at Nato HQ,” a Greenpeace spokesman said.

A Friends of the Earth spokesman noted, in an ironic reference to British reluctance to invest in renewable sources, that: “Perhaps the Russians are worried about our huge wind and solar potential, and have infiltrated the UK government.”

Dedicated anti-shale groups, such as Frack Off and Rising Tide, said their “grassroots” movements depend on ordinary people’s concerns.

The US is the global leader in shale oil and gas extraction, which relies on fracking - blasting a cocktail of water and chemicals into underground shale deposits.

They also say shale development will “lock” industrialised states into fossil fuel use instead of cleaner energy.

According to US statistics, the Baltic states, France, Germany, Poland, Sweden, and the UK have the largest shale reserves in Europe.

Poland is leading the way in Europe. It has drilled more than 60 exploratory wells and its environment minister, Maciej Grabowski, recently said commercial extraction could begin in Pomerania, on the Baltic Sea coast, by the end of 2014.

A 2013 US study into shale underlined the importance of local geology, however.

The 2013 survey downgraded its 2011 estimate of available shale in Poland’s Lubmin basin from 44 trillion cubic feet to 9 trillion due to geological problems discovered on the road to extraction.

It downgraded Norway’s available shale from 83 trillion cubic feet to zero.